[PATCH] Some infrastructure work for virtual file system (now on phab)

[Argyrios Kyrtzidis]

On Feb 14, 2014, at 9:26 AM, Rafael Espíndola <rafael.espindola at gmail.com> wrote:

>> So you’re suggesting something like this:
>> 
>> class AbstactFileSystem {
>> …
>>  class FileDescriptor {
>>  public:
>>    virtual ErrorOr<Status> status() = 0;
>>    virtual error_code getBuffer(…) = 0;
>>    virtual error_code close() = 0;
>>  };
>> ...
>> };
> 
> That looks odd. If we can keep it to one virtual interface (like in
> the patch) that would probably be better. On llvm a file descriptor in
> always an int. There is some desire to use a file handles on windows,
> but that is also just a abstract pointer.
> 
> Can't we make the file handle an arbitrary uintptr_t sized object? The
> FileSystem is then able to interpret it in any way it wants.

I find it natural, the file descriptor encapsulates the file operations that you perform on a “file entity” (which can be a virtual file or whatever) and this is what we are modeling.

I would find it unnatural that you have a series of multiplexed AbstractFileSystem objects and you constantly have to thread through them uintptr_t's that every AFS object has to say whether it understands that particular uintptr_t or not.
it could be complicated to have them cooperating on the interpretation of the uintptr_t.

> 
> Cheers,
> Rafael